1. Field of the Invention
The present invention relates to a self-emitting display device, and more particularly, to an apparatus and method for driving a self-emitting display device.
2. Background of the Related Art
Generally, a self-emitting display device spontaneously emits a light when electric power or other energy is applied thereto. There are an organic electroluminescence (EL) display, an inorganic light emitting diode, an inorganic EL display, a field effect display, a plasma display panel, and the like in the self-emitting display device.
The self-emitting display device has good visibility outer illumination is low. On the contrary, the self-emitting display device has poor visibility as outer illumination is high. For example, visibility becomes poor in the outside environment where the intensity of light is high.
Most of the self-emitting display devices have a number of control switches which intermittently vary their emitting luminance or control knobs which gradually vary their emitting luminance, so that a user can control emitting luminance using the control switch or the control knob if the intensity of light in the outside environment is high. However, in this case, since the user should directly control emitting luminance of the display device in accordance with the use environment, there brings the user inconvenience and also there are no benefits in time and effects.
To solve such problems, there has been proposed a method for automatically controlling emitting luminance of a display device in which an optical sensor is used to senses the brightness of the outside environment. This method is adapted to control the brightness of a back light of a liquid crystal display (LCD) not a self-emitting display device. The method for automatically controlling emitting luminance of a display device includes the steps of sensing brightness of the outside environment by the optical sensor, and controlling the electric power applied to the back light in accordance with the brightness to automatically control the emitting luminance of the display device. In this method, in the case that the outside environment is dark, it is determined whether the intensity of light in the outside environment sensed by the optical sensor is less than a reference value. If so, the emitting luminance of the display device increases by increasing the electric power applied to the back light more than the reference value. In the case that the outside environment is bright, the emitting luminance of the display device decreases by decreasing the electric power applied to the back light less than the reference value. As a result, the emitting luminance of the display device can be controlled automatically.
Since this method automatically controls the emitting luminance of the display device, power consumption can be reduced and inconvenience of the user can be removed. However, since the electric power of the back light increases or decreases in accordance with the intensity of light of the outside environment, it makes the sight of the user unstable, thereby causing fatigue to the user. In other words, it is difficult to distinguish images or information characters when the emitting luminance of the display device is too low, while glaring occurs when the emitting luminance of the display device is too high, thereby reducing efficiency of work and causing eyestrain.